Is there a way to temporarily disable limit switches on initial enable?

[Dbl_Tap]

I asked this in the official Mach 4 Forum and no replies as of yet so I figured I'd ask here.

I have my clearpath servos set to home to hard stops when they are enabled by Mach4 for the 1st time after powering them up. I like this function but of course since I have added limit switches they will be triggered just before touching the hard stops and shut things down..

Is there a way to keep the limit switches from being enabled until AFTER the home to hard stops is complete? I know I can have the HLFB output from the servo tell Mach4 several different things so I'm thinking there might be a way to tell Mach to keep the limits disabled until the input tells Mach it is done and ready to go to work.

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[joeavaerage]

Hi,
the HLFB is usually used for signaling a fault to the controller, say an overload condition or a following error. If you want to use the HLFB for some other purpose the you would
lose the ability to signal a fault. Are you sure you want to do that?

You may have seen a button <Axis Limits Override>. May I suggest try using that, I believe it will disable the Limit switches and you will be able to use hardstops. Thereafter you'd
turn the Limits back on.

If that works then with a little scripting you could automate it.

Craig

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Thanks Craig. I appreciate it. I about have my machine rebuilt and set up correctly to the MB3/ESS. I guess my next step will be learning curve of making things work, like my touchplate script, laser on off and zero, etc in Mach4 VS Mach3

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And that doesn't work. Hit the Axis Limits Override button and then enable. As soon as it hits a limit it stops, slightly backs off and disables the servos. Hit enable again and it hits the next axis limit same order of events.

[joeavaerage]

Hi,

As soon as it hits a limit it stops, slightly backs off and disables the servos.

If you hit a limit switch the machine Estops, no ifs or but or backing up any any other crap it just stops.

Hitting the switch then backing up is Homing behaviour. Have you set up the switches as Homes or Limits or both?
I would expect the Override button to have Mach ignore a Limit.....but from what you have described Mach is interpreting your switch as a Home.

Craig

[Dbl_Tap]

Nope, definitely as limit switches. They hit and seem to just barely back off and disengage when they hit it. My homing switches back off the .10 I have specified.

[Dbl_Tap]

If I hit the limits when I'm just jogging them myself they don't appear to have this back off behavior. I have to override them and jog off of it. It's only when I'm using the servo's home to hard stops at enable they do this.

[joeavaerage]

Hi,

It's only when I'm using the servo's home to hard stops at enable they do this.

That rather suggests that when the machine is Homing...and I take it your intention is to use the hardstops, then the limit switches are being treated as Home events,
whether you set it up that way or not.

Craig

[Teknic_Servo]

Hi Chris,

I am an applications engineer at Teknic and came across this post. I want to provide some additional information on the ClearPath motor’s digital output, HLFB (High-Level Feedback).

You can configure HLFB to let you know when you’ve finished making a move (without losing the ability to know if the motor has faulted). HLFB, as you’re likely aware, is a user-configurable digital output which can be set into various modes, each of which outputs a number of different motor statuses. ClearPath's HLFB output can, depending on the mode, simultaneously provide the following data to your controller: real-time torque usage, Move Done (including when you’ve finished a homing move), In-position, and fault status.

A detailed discussion of all HLFB modes is covered in the ClearPath User Manual. I’d encourage you to review them and feel free to contact us if you have any questions. Please note that some HLFB modes provide multiple statuses and will require that you program your controller to identify them. I have not personally used the Mach4 controller, but based on joeavaerage’s comments above, it sounds like you can program/configure your controller in a number of different ways. So there should be an HLFB mode that will work for you.

If you have any other questions about ClearPath’s HLFB output or want to discuss your project with an applications engineer, please feel free to contact us at https://teknic.com/contact/ or give us a call (585-784-7454).

-Ian R. – Teknic Applications Engineer

[joeavaerage]

Hi,
still the problem is that if you use hardstops as your machine home then ANY switches you provide as extra must perforce be 'inside' the machine home????
So what good is a machine home to you that is outside the boundaries of the machine?

For example if you wish to use g28 or g28.1 then the machine will drive to machine home....but it will encounter a limit switch BEFORE it gets there and presumably Estop.

Many tool change routines and many rotary tool paths use g28, g28.1 and g30 as a safe retract location, ie machine zero.

I would suggest that if you want to use hardstops as the home location then you'll have to apply a HomeOffset (Control/Homing,SoftLimits tab) to at least put the machine zero 'inside' the limit switches.

Craig